Expansive drill bit



Mar. 20, 11-923.

1 J. P. MILLER EXPANSIV E DRILL BIT 5, 1921 2 she ts-sheet 1 Filed Aug.

ATTORNEYS 20, 1923. J. P. MILLER EXPANSIVE DRILL BIT 2 sheets-sheet 2 Filed Aug. 5, 1921 JR Miller,

ITO/mks Patented ar. 2o, 192a if IHTED STTES JESSE PERKINS-MILLER, OF HOUMA, LOUISIANA, ASSIGNOR F ONE-HALF T0 J. H.

- THATCH'ER, OF HOUMA, LOUISIANA.

EXPANSIVE DRILL BIT.

Application filed -August'9l, 1921. Serial No. 489,522.

To all whom it mar concern: I

Be it known that. I, Jnssn PERKIN MILLER, a citizen ofthe United States, and

tion is to providea drill bit, the blade ofv which expands or spreads when weight is imposed thereon.

A further object of the invention is to pro-,

' vide a drill bit including a holder or collar formed with a socket provided with a slot and such an arrangement of bevels that the blades are caused to spread when slid up the slot, to drill a hole larger thantthe diameter of the casinginwhi'ch the drill operates.

Other objects and advantages" will appear .in the followingspecification, reference being had to theacoompanying drawings in which:

Figure 1 is a-side elevationvof the improved'expansive'drill bit, the blades being shown hanging in the normally collapsed position,

Figure 2 is a section on the line..22 of Figure 1, showing the blades collapsed in full lines and spread in dotted lines,'the latter position being assumed when weight is imposed on the bit,

Figure 3 is a sectional perspective view illustrating the position assumed by one of weight is imposed on the the blades when bit, I

Figure at is a plan View of the upper end of the bit collar, showing the drilling water hole, and

Fiureo is a detail horizontal section on the line 5-5 of Figure 2. Y 5

It is one of the principal purposes of the invention to provide a drill bit, the'blades of which will expand or spread when weight -is imposed thereon, thereby to drill ahole of a diameter larger (or at least as large) as the casing in which the bit works. In Figure 2, theblades 1 and.2 are each provided with opening bevels 3 and 4. c When full line the lower extremities of the blades strike the bottom of the hole, they naturally stop, and as the weight of the holder or collar 5, and other superposed parts, descends upon the blades, the opening bevels 6 at the sides of the slot 7 engage the bevels 3 and 4, and

cause the blades 1 and 2 to spread from the position to the position shown in dotted lines.

' It is Wholly by means of the weightimposed on the bevels 3 and 4 that the-blades 1 and 2 are caused to spread as stated. Each blade is also provided with a beveled shoulder '8 and 9' forthe purpose of resting against the bevels 6 and providing solid supporting shoulders to receive the thrust imposed on the blades. The slot 7 is of rectangular formation,.asshown in Figure 5, so as to snugly contain the upper parts or shanks 10 of the blades. It is intended that there shall be no excessive loose motion of the shanks, and the slot 7 may be fi-lled with grease for the purpose of lubricating the moving parts and at the same time exeluding water and dirt in a large measure. 'A pivot pin 11 holds the blades together. Pins 12 retain the blades on the collar 5. The upper end of each shank 10 is provided with shoulders 13' which engage the pins 12 at the respective sides and keep the blades from dropping out of the slot? when they assume the normal collapsed position.

A groove 14 below each of the shoulders, provides room for the upward movement of the blades past the retaining pins 12. The

collar 5 isprovided with holes 15 through point of which drilling water passes to the operation of the blades 1 and 2.

The operation may be briefly reviewed to advantage." In letting the drill bit down v into'the casing, the blades 1 and 2 hang as shown in full lines in Figure 2. They are pivoted togetherby the pin 11. The blades are so proportioned that they hang together,

'their'lateral edges lying flush-with each other.

Imagine the collar 5 moving down upon the blades, and the blades as having been stopped by the bottom of the hole. The bevelsj6 will first engage the opening bevels 3 and 4 of the blades and cause the latter to spread, the blade 1 toward the right and the blade 2 toward the left, until they finally assume the dotted line position. Each blade its - has a straight side 16 opposite its opening bevel, to accommodate the spreading actionjust described. Any type of blade may be used in the collar 5; fishtail, .diamond point, drag, or rollers orv discs. The fishtail type. of blade (shown in the drawing) is the most common and useful shape. The advantage of employing the principle of operationintended to .be employed in connection With this bit (the superposition of weight on the bit blades) is to insure the cutting of a hole larger than the diameter of the casing andkeeping that diameter relatively uniform. The wear on the blades and consequent-reduction in the diameter of the hole as the depth increases, is compensated for by the 1 initiallylarger diameter of the hole. Therefore there is little danger of drilling the hole smallerthan the casing with the consequent diiiiculty of having the casing bind when driven farther.

While the construction and arrangement" of the improved expansive drill bit as herein described and claimed, is that of a generally preferred form, obviously modifications and changes may be made without departing from the spirit of the invention or the scope of the claims.

I claim 2- r 1. A drill bit comprising a holder provided with a socket opening through one end thereof and having a slot formed through its walls at the edge of thesocket, saidslot 'being provided with a bevel, and a drillblade having the shank thereof-slidably disposed within the socket and being provided with a bevel adapted to engage the bevel of the slot to occasion a lateral'movement of the free end of the blade when the weight of the holder is superimposed upon the blade.

2. A rotary drill bit, comprising a collar with a slot having opening bevels, and a air of blades each having an openlng bevel in line with those of the slot to be engaged by the latter whenthe collar moves down, i

to spread the blades by its weight.

3. .A rotary drill bit, comprising a casing having a slot with lateral opening bevels, blades pivoted to normally hang together in the collapsed position, each having a bevel on one side and a straight portion on the other, the bevels and straight-portions being on-opposite sides of the respective blades, the bevels of the slot. engaging those of the blades when the collar moves down to spread and lock the blades; and means associated with the slot and blades to limit the separating movement of the blades and collar.

4. A rotary drill bit, comprising a collar with a slot having opening bevels on opposite sides, a pair of blades with shanks extendinginto the slot and pivoted at the top,

shoulders formed adjacent the top of the shank, retaining pins traversing the slot to support the blades when normally collapsed,

and an openingbevel on one-side of each blade, with a straight portion on the opposite side of the same blade, said openingbevels being engaged by those of the collar when the latter is let down, to spread the "blades beyond the circumference of the collar.

5. A, drill bit comprising a holder provided with an axial socket opening through JEssE PERKINS MILLER. 

